1. Technical Field
The present invention relates generally to airbag module control systems and more particularly to an electronic controller for an airbag module control system.
2. Discussion
Modern vehicles are typically equipped with one or more airbags which are controlled by an electronic controller. The electronic controller analyzes data received from a variety of sensors located throughout the vehicle and determines whether to inflate the airbag and in some systems, the rate at which the airbag should be inflated. Despite the significant benefits derived generally from the use of such airbag modules, there are circumstances under which an airbag should not be deployed.
Several control systems have been developed to automatically determine when such circumstances exist. These control systems typically rely on a plurality of sensors to detect or quantify a plethora of variables which are employed in an attempt to quantify the relationship between a seating area and the person or object placed in the seating area. Such systems have not been received with commercial acceptance due to their cost, inability to completely identify all situations in which an air bag module should not be deployed and/or the extreme difficulty incurred to incorporate them into a vehicle after it has been manufactured. Consequently, many consumers simply prefer a system which permits one or more air bag modules to be selectively disabled.
The disabling systems known in the art have relied on a switch which mechanically breaks or interrupts the squib circuit used to initiate the inflation of an air bag. Despite the apparent success of such systems, several drawbacks are apparent.
Several of these drawbacks relate to the mechanical interruption of the electronic squib circuit and the effect this has on the integrity and reliability of the air bag module. Such drawbacks include the potential for error when installing the switch, the inability to detect failed or burned out indicators and the inability of the air bag controller to perform diagnostics on all new circuits.
Another significant drawback relates to the use of such system with sophisticated, multi-stage air bag modules. Modern, sophisticated air bag modules utilize inflators which typically employ two or more squib circuits, each of which are deployable independently of the others. Deployment of the squib circuits is controlled according to a deployment methodology which generally tailors the deployment rate (i.e., inflation rate) to the magnitude of the collision.
Consequently, where multiple squib circuits are utilized, mechanical disablement of the squib circuits would require several switches. In such a system, effectively disabling an air bag module would require that all of the switches be set to mechanically interrupt their respective squib circuits; a failure to set a single switch correctly would prevent the air bag module from functioning as had been intended.
Accordingly, there remains a need in the art for a vehicle occupant restraint system which permits air bag modules having two or more squib circuits to be disabled in a convenient and reliable manner. There also remains a need in the art for a vehicle occupant restraint system which can be easily and reliably upgraded with controls permitting the vehicle occupants to selectively disable one or more air bag modules.